Is it normal for antibiotics to make your tummy swollen, to the point where you look 6 month pregnant?!?

I finished a couse of ofolaxillin yesterday morning. from the start of my 7 day course, my tummy swelled right up, and i have been feeling huge movements like baby kicks. I actually did a pregnancy test i was so worried, and even tho that was neg, i've still worried that i could be preg, as my belly is huge and the feeling is so intense. I finished the course 36 hrs ago, and my tummy doesn't seem to be deflating. i know it's not fat as it's really hard!! so could it be the antibiotics, can they give you digestive problems to that extent, and if so, when should i expect to deflate?!?!